Cement masons, who usually work for contractors in the building and construction industries, apply the concrete surfaces in many different kinds of construction projects, ranging from small patios and sidewalks to highways, dams, and airport runways. Cement masons' responsibilities include building forms for holding the concrete, determining the correct mixture of ingredients, and making sure the structure is suitable to the environment. According to the U.S. Department of Labor, approximately 135,200 cement masons and concrete finishers are employed in the United States.